The present invention relates to a belt conveyor and has particular reference to a conveyor with an endless conveying belt band and associated deflecting rollers and intermediate rollers.
Belt conveyors of this kind are known, in which the belt is driven by means of a friction wheel. Thus, for example, in German Patent Specification No. 34 21 413 there is described a belt conveyor in which a friction wheel is arranged between runs of the conveyor belt and the runs are urged against the friction wheel by means of counterpressure rollers engaging from the outside. It is evident that, to achieve a predetermined coefficient of friction, the pressure between the friction wheel and the belt must be stronger the greater are the peripheral forces to be transmitted to the belt for drive thereof. In order to ensure a reliable drive even at maximum loading, the pressure between the friction wheel and the conveyor band must therefore be set to the highest possible loading. This has the disadvantage that the belt is highly stressed in the region of engagement of the friction wheel even in the case of idling, and thus a high degree of wear arises both at the friction wheel and the belt.
In the case of the conveyor described in the afore-mentioned patent specification, the belt has a curved path. When curved path belt conveyors of that kind are highly loaded, blockages of the belt can occur, with the consequence that the friction wheel overruns and possibly grinds through the belt at the point of engagement. This danger exists particularly when the contact pressure between the belt and the friction wheel is too low. However, lowering of the contact pressure can easily occur during operation, as the friction coating of the friction wheel may become thinner due to wear in the course of time and the contact pressure force then reduces.